title: Molecular mechanisms that drive estradiol-dependent burst firing of Kiss1 neurons in the rostral periventricular preoptic area.
abstract: Kisspeptin (Kiss1) neurons in the rostral periventricular area of the third ventricle (RP3V) provide excitatory drive to gonadotropin-releasing hormone (GnRH) neurons to control fertility. Using whole cell patch clamp recording and single-cell (sc)RT-PCR techniques targeting Kiss1-CreGFP or tyrosine hydroxylase (TH)-EGFP neurons, we characterized the biophysical properties of these neurons and identified the critical intrinsic properties required for burst firing in 17β-estradiol (E2)-treated, ovariectomized female mice. One-fourth of the RP3V Kiss1 neurons exhibited spontaneous burst firing. RP3V Kiss1 neurons expressed a hyperpolarization-activated h-current (Ih) and a T-type calcium current (IT), which supported hyperpolarization-induced rebound burst firing. Under voltage clamp conditions, all Kiss1 neurons expressed a kinetically fast Ih that was augmented 3.4-fold by high (LH surge-producing)-E2 treatment. scPCR analysis of Kiss1 neurons revealed abundant expression of the HCN1 channel transcripts. Kiss1 neurons also expressed a Ni(2+)- and TTA-P2-sensitive IT that was augmented sixfold with high-E2 treatment. CaV3.1 mRNA was also highly expressed in these cells. Current clamp analysis revealed that rebound burst firing was induced in RP3V Kiss1 neurons in high-E2-treated animals, and the majority of Kiss1 neurons had a hyperpolarization threshold of -84.7 mV, which corresponded to the V&frac12; for IT de-inactivation. Finally, Kiss1 neurons in the RP3V were hyperpolarized by μ- and κ-opioid and GABAB receptor agonists, suggesting that these pathways also contribute to rebound burst firing. Therefore, Kiss1 neurons in the RP3V express the critical channels and receptors that permit E2-dependent rebound burst firing and provide the biophysical substrate that drives the preovulatory surge of GnRH.
authors.affiliation: Department of Physiology and Pharmacology, Oregon Health and Science University, Portland Oregon;
authors.forename: Chunguang
authors.initials: C
authors.lastname: Zhang
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Tonsfeldt
authors.forename: Jian
authors.initials: J
authors.lastname: Qiu
authors.forename: Martha A
authors.initials: MA
authors.lastname: Bosch
authors.forename: Kazuto
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Robert A
authors.initials: RA
authors.lastname: Steiner
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Kelly
authors.forename: Oline K
authors.initials: OK
authors.lastname: Rønnekleiv
mesh_terms: D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D005498:Follicular Phase / Q000187:drug effects / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D059648:Kisspeptins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010052:Ovariectomy; D011301:Preoptic Area / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D009435:Synaptic Transmission / Q000187:drug effects / Q000235:genetics; D020542:Third Ventricle / Q000187:drug effects / Q000378:metabolism
chemical_list: C491407:Kiss1 protein, mouse; D059648:Kisspeptins; D049452:Green Fluorescent Proteins; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol
keywords: RP3V; T-type calcium channel; burst firing; kisspeptin; pacemaker current